1. 1 Semmelweis University Faculty of Dentistry, Budapest Studium: Radiation Protection/Strahlenschutz, 2011/2012 PUBLIC EXPOSURES (Strahlendosen für die Bevölkerung) 26. October, 2011, 16:00-17:10 Room: Árkövy Béla Kanyár hab. PhD, Semmelweis Univ., Radiation Protection Service

2. 2 External and Internal Radiation Dose Committed dose: ∫ D(t) dt τ 0 According to regulation: τ = 50 y (adults), 70 y (children) external internal (by intake of radioisotopes) τ time ˚ Dose rate

3. 3 Categories of Exposures (with respect to the regulation) Occupational exposures (Berufliche …) Public (incl.: Medical?) exposures (Non-human Biota exposures ?)

4. 4 Sources of Public Exposures Natural Exposure (Natürliche…) annual impact:  2.5 mSv effective dose (external + internal) Artificial Exposure (Künstliche …) annual impact:  1.7 mSv effective dose (mainly due to medical, X-ray diagnostics)

5. 5 Natural: Cosmogene and terrestrial radionuclides Univerzum (ions, α-, β-, n-, müon- … radiation) γ n γ Atmosphere Earth Surface Raindr.

6. 6

7. 7 Terrestrial exposure: natural radioactive decay series (r. nuclides mainly in soil) Pb-208 stabile Rn-220 32 s Th-232 T=14 mrd y... U-235 T=0.72 mrd y Actinium serie Uranium serie Thorium serie Rn-219 3,9 s Pb-207 stabile U-238 T=4.5 mrd y Rn-222 3,8 day Pb-206 stabile... Main processes: Rn-emanation: deliberation of Rn molecules from chem.-phys.binding in solid phase of soil (to gas form in soil) Rn-exhalation: outflow of Rn gas from soil to atmosphere.

8. 8 Rn-222 concentrations indoor and outdoor In winter: due to small ventilation, the Rn-gas accumulates indoor Living room (indoor) 100-500 Bq/m 3 soil Rn-222 (noble gas ) Outdoor, air: 5-10 Bq/m 3, to height of nearly 200-300 m exhalation ventilation 500-2000 Bq/m 3 Rn-222 Ra-226 Rn-222 „cultural man”: 80 % indoor α

9. 9 Rn-conc. due to periodic ventilation, for short (minutes) time intervals C Rn (Bq/m 3 ) 300 200 100 Short and periodic ventilations, 5-6 hourly 6 h 9 h 12 h 15 h 18 h

10. 10 Artificial exposures The main sources of the impact are: - contamination of air, soil, vegetation etc. in the close environment of: nuclear power plants (NPP) and isotope labs, due to discharges of radionuclides - contamination of spring waters in the close environment of Radioactive Repositories Medical patient: X-ray diagnostic tests,…

11. 11 irrigation Source Atmosph Surface water Soil Vegetables Feeding vegetation Animals, anim. prod. water plants, fishes Man Sediment inhalation A radioaktív anyag migrációja a bioszférában és besugárzási útvonalak az ember esetén (szaggatott nyíl a sugárzás, folyamatos nyíl a radioaktív anyag terjedését jelöli) Transport, migration of radionuclides discharged from NPP/isotope lab. Exposure pathways (Expositionspfaden). external expos. intakes

12. 12 Atmospheric dispersion near to the source In „normal practice”, 2-3 km far from the NPP no contamination are detected, only assessments are provided from the discharges and meteorological parameters (fequently used: Gaussian plume model)

13. 13 Averaged dose levels, inc. confidence ranges (natural sources) Table 10. Worldwide average annual doses in the environment (dose to the human body). The ranges correspond to about a 90% confidence interval Sources, pathwaysMean values and ranges (mSv) Cosmic rays, external, annual effective dose0.38 (0.3-1.0) Inhalation and ingestion of cosmogene radionuclides (internal, committed effective dose, annual) 0.012 (0.008– 0.02) Terrestrial, external, annual effective dose, outdoor, indoor 0.45 (0.3-0.6) 0.55 (0.4-0.8) Terrestrial, annual internal, committed eff. dose (without Rn and daughters) 0.27 (0.2-0.5) Terrestrial, annual internal, comitted eff. Dose from the Rn daughters1.2 (0.5-5.0) Terrestrial, annual internal, committed equivalent dose to lung, due to Rn daughters 10 Technical Enhanced Natural Occurring Radioactive Material (TE- NORM): indoor (building material: Ra-226 content), …

14. 14 Averaged individual doses to public (artificial sources) Table 10. Worldwide average annual doses in the environment (dose to the human body). The ranges correspond to about a 90% confidence interval Sources, componentsMean and range (mSv) Medical, external (mainly X-ray diagn),annual effective dose 1.5 (0.1-5) From NPP (1-5 km far), annual 0.01 ( - 0.1) Atomic bombs (Hirosima, Nagaszaki, inside the city area) 100-5000 Nuclear tests, North hemisphere0.1-2, South< 0.01 Chernobyl accident, effective dose within r ≈ 30 km circle1-20 Central and West Europe0.1-2 North America0.01 Japan0.01 South hemisphere< 0.01 SE X-ray stations, eff. dose by films (-2009, last 3 years): ≈ 0.5 mSv / y SE dentist X-ray stations (last 3 years): < 0.3 mSv / y SE nuclear medic. labs (last 3 years): ≈ 0.7 mSv / év

15. 15 Medical exposure (patient dose per test)

16. 16 Hírsugár (2007. júliusi száma), Sugárhumor/Déri Zsolt (Eötvös Loránd Fizikai Társulat Sugárvédelmi Szakcsoport)

17. 17 External dose: nearly 100 % in medical, dental praxis - X-ray diagn., Radiation therapy - Meassurement of X-rays (≈ 60 keV 20-150 keV): mainly by ionization chamber (energy dependency) Internal dose: Radioactive isotopes: used as tracers to test the metabolic systems (nuclear medicine), and in internal radioisotope therapy (I-131 to thyroid) Dose assessment: Calculation from measured radionuclide concentration of air and food samples (inhalation and ingestion dose). - α-, β- and γ-ray contamination of whole body, surfaces, samples etc.: special sample processing, detectors: NaI(Tl), semiconducter ones (Ge, Si) Determination of exposures

18. 18 „Rainpeaks”: due to intensive wash out to the surface, from atmosphere Environmental monitoring, early warning system Continously (mainly by 2-10 minutes frequency) measured dose rates, usually 1 m heigh from the surface

19. 19 Personel monitoring, dose meters

20. 20 Whole body counter, determination incorporated radionuclides (geometries used) detector

21. 21 Scanning whole body counter with two detectors (Pb etc shielding to minimize the effect of outside background)

22. 22 A Cs-137 in the inhabitans of capital Budapest (measured by: Andrási, A., …(KFKI)) Atmospheric nuclear tests (SU-USA: 1945-1964), later on by less intensity: Fr, GrB, China,…) Activ./body weight

23. 23 90 Sr contamination (pure β-emitter, sample measurements) Milky tooth Permanent tooth

24. 24 Literature: Basic safety standards. IAEA Safety Series No. 115, Vienna, 1996) Kanyár, B., G. J. Köteles: Dosimetry and Biological Effects of Ionizing Radiation, Chapter 10, in: Vértes, A., Z. Klencsar (eds): Handbook of Nuclear Chemistry, Springer, 2010 UNSCEAR Reports (2-4 yearly, UN NewYork, …) EU Radiation Protection No. 136, 2004. European guidelines on radiation protection in dental radiology ICRP (Intern. Comm. on Radiol. Prot.) Public. No 103, Pergamon P., NewYork, London, 2007.